1. Field of the Invention
The present invention relates generally to a two-directional pressure relief assembly for use in a fluid transportation system and in particular to a rupture disk assembly having an eccentric groove or score line formed in a flange portion of the disk assembly for relieving pressure in a safe manner.
2. Description of Related Art
Relief devices of the type commonly known as rupture disks have been utilized by the industry for many years to provide a safety mechanism to relieve excessive pressure from an over-pressurized system or vessel in a reliable manner. Through the years, numerous improvements have been made in the rupture disk in order to reduce the cost and to improve its simplicity and reliability.
One type of disk is known as the reverse buckling rupture disk and is positioned in the system such that a dome formed with the disk is positioned in the vent pointing towards the pressure side of the vent. Thus the convex side of the dome faces the upstream side of the vent wherein pressurized fluid is located. Such disks can be operated at pressures that are very close to the bursting pressure of the disk. The dome collapses when fluid pressure reaches a preselected pressure for which the dome is designed. As the dome is ruptured, it is forced in the direction of the downstream side of the system.
It is important that the elements of the rupture disk be retained by the remainder of the disk after being ruptured. If any portion of the rupture disk escapes into the fluid system, it can cause damage to valves and other equipment. Thus it is extremely important that the rupture disk dome and any portions thereof remain intact after rupture and remain attached to the assembly in which they are mounted.
The prior art utilizes several methods of ensuring proper rupture while retaining the parts of the ruptured disk with the mounting elements. Some use knives to cut the dome when it is ruptured and form a pattern so as to cause petals that are held to a flange portion of the disk by tabs. Others use grooves, scores, or etchings on the dome of the reverse buckling rupture disk. When such a device ruptures, it fractures along the lines of weakness produced by the grooves so as to form petals that are held by flange portions to the remainder of the assembly.
It would be advantageous to have a rupture disk assembly that provides progressively more resistance to tearing as the tear progresses. Such a device could be formed to begin its tear or rupture at a predetermined pressure but would become more difficult to rupture because of the increasing resistance, thus reaching a point where the rupture stops leaving a large area to retain the ruptured portion in the remainder of the assembly.